Electrochemical performance and modeling of lithium-sulfur batteries with varying carbon to sulfur ratios

Abstract

Summary Lithium‐sulfur batteries have attracted much research interest because of their high theoretical energy density and low‐cost raw materials. While the electrodes are composed of readily available materials, the processes that occur within the cell are complex, and the electrochemical performance of these batteries is very sensitive to a number of cell processing parameters. Herein, a simple electrochemical model will be used to predict, with quantitative agreement, the electrochemical properties of lithium‐sulfur cathodes with varying carbon to sulfur ratios. The discharge capacity and the polarization were very similar for the lowest sulfur loadings, while above 23.2 wt% sulfur the gravimetric capacity dropped significantly, and there was an increase in the cell polarization. In addition, a transition in the electrode morphology, from well dispersed to aggregated sulfur at the surface, will be reflected in the change in a critical model parameter demonstrating the sensitivity and functionality of even this simple model in predicting complex behavior in the lithium‐sulfur cells.

Modeling the discharge behavior of a lithium‐sulfur battery

“…Lithium-Sulfur (Li-S) batteries have gained major consideration in recent years due to their high theoretical gravimetric energy density and high-capacity, inexpensive and abundant cathode materials. [1][2][3][4][5][6] In Li-S batteries, the battery performance depends vastly on cell design because of the complex mechanisms taking place in the cell. [1][2][3][4][5] Carbon-to-sulfur (C/S) and electrolyte-to-sulfur (E/S) ratios in the cell are commonly investigated examples of these design factors that define the battery performance.…”

“…[1][2][3][4][5][6] In Li-S batteries, the battery performance depends vastly on cell design because of the complex mechanisms taking place in the cell. [1][2][3][4][5] Carbon-to-sulfur (C/S) and electrolyte-to-sulfur (E/S) ratios in the cell are commonly investigated examples of these design factors that define the battery performance. [1][2][3][4] C/S ratio determines the electrochemical surface area in the cathode along with its electronic conductivity and thus has a key impact on the cathode kinetics.…”

Freestanding graphitic carbon nitride‐based carbon nanotubes hybrid membrane as electrode for lithium/polysulfides batteries

“…3 However, there are still few technical challenges to the commercialization of lithium sulfur batteries, such as poor conductivity of kinetics of sulfur, shuttle effect of redox reaction intermediates, and volume expansion due to density differences between sulfur and Li 2 S. 4,5 Recently, many efforts have been made by researchers to address the above problems. 6,7 The nanostructured carbon or doping them with heteroatoms (nitrogen, oxygen, phosphorus, and sulfur) as conductive framework were used as sulfur matrices, 8 such as porous carbon, 9 graphene, 10 conductive polymers, 11 and their hybrids. 12 Such approaches could promote the ions/electrons transport to suppress the dissolution of lithium polysulfide by confining sulfur to pores having a conductive skeleton.…”

Synergistic effect of sulfur on electrochemical performances of carbon‐coated vanadium pentoxide cathode materials with polyvinyl alcohol as carbon source for lithium‐ion batteries

“…Sulfur is deemed to be as the most promising cathode active material for a new generation of lithium‐ion battery (lithium‐sulfur battery), owing to their high theoretical specific capacity (1675 mAh g −1 ), low cost, and environmentally friendly . However, the insulation and volume of the sulfur and polysulfide “shuttle effect” limits its specific capacity and cycle life .…”

“…[15][16][17] Sulfur is deemed to be as the most promising cathode active material for a new generation of lithium-ion battery (lithium-sulfur battery), owing to their high theoretical specific capacity (1675 mAh g −1 ), low cost, and environmentally friendly. [18][19][20] However, the insulation and volume of the sulfur and polysulfide "shuttle effect" limits its specific capacity and cycle life. 21,22 In order to deal with these problems, many researchers believe that sulfur is required to be hosted on some matrix materials, such as carbon material, 23 metal compounds, 24,25 conductive polymer materials, 26,27 and so on.…”